Variable Displacement Compressor

ABSTRACT

A linkage mechanism ( 40 ) of a variable displacement compressor includes an arm ( 41 ) extending from a rotating member ( 21 ) toward a tilting member ( 24 ), an arm ( 43 ) extending from the tilting member ( 24 ) toward the rotating member ( 21 ) and receiving rotary torque from the arm ( 41 ) of the rotating member, a pin ( 51 ) fixed to one of the arm ( 41 ) of the rotating member and the arm ( 43 ) of the tilting member, and an axial direction load receiving face ( 53 ) formed on the other of the arm ( 41 ) of the rotating member and the arm ( 43 ) of the tilting member and configured to contact with the pin ( 51 ) to receive axial a direction load applied between the rotating member ( 21 ) and the tilting member ( 24 ).

TECHNICAL FIELD

The present invention relates to a variable displacement compressorhaving a linkage mechanism.

BACKGROUND ART

A variable displacement compressor includes a drive shaft, a rotor thatis fixed to the drive shaft and rotates integrally with the drive shaft,a swash plate (cam plate) that is attached to the drive shaft andchangeable its tilt with respect to the axis of the drive shaft, alinkage mechanism that links the rotor and the swash plate, and pistonsthat are engaged to the swash plate. When the drive shaft rotates, theswash plate rotates with the rotor and the piston reciprocatescorresponding to the inclination angle of the swash plate. The linkagemechanism links the rotor and the swash plate so that the inclinationangle of the swash plate can be changed as transferring the rotation ofthe rotor to the swash plate. With this, the piston strokes are changedby changing the inclination angle of the swash plate so as to change thedischarging amount (see Japanese Patent Laid-Open No. 2004-068756, forexample).

The conventional linkage mechanism includes a projection extending fromthe rotor toward the swash plate and a projection extending from theswash plate toward the rotor. The projection of the rotor and theprojection of the swash plate overlap each other in the rotatingdirection and, with this structure, rotary torque from the rotor istransferred to the swash plate. The projection of the swash plateslidably contacts with a base of the projection of the rotor. The baseof the projection of the rotor functions an axial direction loadreceiving face for receiving an axial direction load applied to theswash plate. The inclination angle of the swash plate changes with theslide of the projection of the swash plate on the pressure receivingface.

DISCLOSURE OF THE INVENTION

With such a conventional structure, the inclination angle of the swashplate is changed while a large compression reaction force (the axialdirection load) from the pistons is applied to the contact between theaxial direction load receiving face and the projection of the swashplate so that the contact are easily worn. Accordingly, the contact arerequired to be quenched or the like in order to enhance their hardnessand to prevent such damages. If the contact are worn down compared tothe initial condition, the upper dead center of the each piston islowered so that the compressive performance of the compressor may bedecrease.

The contact between the axial direction load receiving face and theprojection of the swash plate are formed in a complicated shape so thatthe inclination angle of the swash plate varies as the projection of theswash plate slides on the axial direction load receiving face. Since thecontacting face is formed on the projection of the rotor or the swashplate, difficult processing is required and manufacturing costincreases.

The present invention is made based on such a conventional technique. Anobject of the present invention is to provide a variable displacementcompressor capable of preventing an abrasion of a portion where a largeaxial direction load is applied and reducing manufacturing cost of thevariable displacement compressor.

An aspect of the present invention is a variable displacementcompressor, including: a drive shaft; a rotating member fixed to thedrive shaft and rotating integrally with the drive shaft; a tiltingmember attached to the drive shaft and being changeable a tilt thereofwith respect to an axis of the drive shaft; a linkage mechanismconfigured to rotate the rotating member and the tilting memberintegrally as allowing the tilt of the tilting member; and a pistonconfigured to reciprocate in a cylinder bore corresponding to rotarymovement of the tilting member. The linkage mechanism includes an armextending from the rotating member; an arm extending from the tiltingmember and overlapping with the arm of the rotating member in a rotatingdirection; a pin fixed to one of the arm of the rotating member and thearm of the tilting member; and an axial direction load receiving faceformed on the other of the arm of the rotating member and the arm of thetilting member and configured to contact with the pin to receive anaxial direction load applied between the rotating member and the tiltingmember.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view showing a variable displacementcompressor in a full stroke condition according to an embodiment of thepresent invention;

FIG. 2 is a cross-sectional view showing the variable displacementcompressor in a no-stroke condition;

FIG. 3 is a perspective view showing an assembly of a drive shaft, arotor, and a swash plate of the variable displacement compressor in afull stroke condition;

FIG. 4 is a perspective view showing the assembly of the drive shaft,the rotor, and the swash plate of the variable displacement compressorin a no-stroke condition;

FIG. 5 is a side view showing the assembly taken along the arrow V-V inFIG. 3;

FIG. 6 is a side view showing the assembly taken along the arrow VI-VIin FIG. 4;

FIG. 7 is a cross-sectional view showing a pin of a linkage mechanism inthe variable displacement compressor;

FIG. 8 is a perspective view showing the first modification of the firstembodiment corresponding to FIG. 3;

FIG. 9 is a perspective view showing the second modification of thefirst embodiment corresponding to FIG. 3; and

FIG. 10 is a perspective view showing the third modification of thefirst embodiment corresponding to FIG. 3.

DETAILED DESCRIPTION OF THE INVENTION

A variable displacement compressor according to an embodiment of thepresent invention and a linkage mechanism used therein will be explainedwith reference to the drawings.

Firstly, an over all structure of the variable displacement compressorwill be explained with reference to FIGS. 1 and 2. FIG. 1 shows a fullstroke condition and FIG. 2 shows a destroke condition.

As shown in FIGS. 1 and 2, a variable displacement compressor 1 includesa cylinder block 2, a front head 4 attached to a front end of thecylinder block 2, a rear head 6 attached to a rear end of the cylinderblock 2 via a valve plate 9. The cylinder block 2, the front head 4, andthe rear head 6 are fixed to each other by a plurality of penetratingbolts B and compose a housing of the compressor.

The cylinder block 2 is formed in a substantially cylindrical shape andhas a plurality of cylinder bores 3 placed evenly spaced apart in acircumferential direction. The front head 2 is attached to the front endof the cylinder block 2 and has a crank chamber 5 therein. The rear head6 is attached to the rear end of the cylinder block 2 via the valveplate 9 and has a suction chamber 7 and a discharge chamber 8 therein.

The valve plate 9 is formed with suction ports 11 that communicates thecylinder bores 3 with the suction chamber 7 and is formed with dischargeports 12 that communicates the cylinder bores 3 with the dischargechamber 8.

A valve system (not shown) adapted to open and close the suction ports11 is provided on the valve plate 9 at the cylinder block side. On theother hand, a valve system (not shown) adapted to open and close thedischarge ports 12 is provided on the valve plate 9 at the rear headside. A gasket is interposed between the valve plate 9 and the rear head6 for providing an airtight sealing property between the suction chamber7 and the discharge chamber 8.

A drive shaft 10 is supported by bearings 17, 18 in support holes 19, 20that are formed at centers of the cylinder block 2 and the front head 4so that the drive shaft 10 is rotatable in the crank chamber 5.

the crank chamber 5 accommodates a rotor 21 as a “rotating member” fixedto the drive shaft 10, a swash plate 24 as a “tilting member” attachedto the drive shaft slidably in the axial direction and tiltably withrespect to the axis of the drive shaft, and a linkage mechanism 40 forlinking the rotor 21 and the swash plate 24. The linkage mechanism 40links the rotor 21 and the swash plate 24 so that the rotor 21 and theswash plate 24 rotate integrally as allowing changes of the inclinationangle of the swash plate 24. The swash plate 24 includes a hub 25attached to the drive shaft 10 and a swash plate body 26 fixed to a bosssegment 25 a of the hub 25. To the swash plate body 26 of the swashplate 24, a piston 29 is linked via a pair of hemispherical-shaped shoes30, 30. The pistons 29 are slidably fit in each cylinder bore 3.

When the drive shaft 10 rotates, the rotor 21 rotates integrally withthe drive shaft 10, and the swash plate 24 rotates corresponding to therotor 21 via the linkage mechanism 40. The rotation of the swash plate24 is converted into a reciprocating movement of the pistons 29 by thepairs of piston shoes 30, 30 so that the pistons 29 reciprocate in thecylinder bores 3. By the reciprocation of the pistons 29, refrigerant inthe suction chamber 7 is sucked into the cylinder bores 3 through thesuction ports 11 of the valve plate 9 to be compressed, and thendischarged to the discharge chamber 8 through the discharge ports 12 ofthe valve plate 9.

Control of Variable Capacity

In the variable displacement compressor, a pressure control mechanism isprovided. The pressure control mechanism is configured to adjust adifference in pressure (pressure balance) between the crank chamberpressure Pc in back of the pistons 29 and the suction chamber pressurePs in front of the pistons 29 is provided in order to change theinclination angle of the swash plate 24. The pressure control mechanismincludes a gas extraction passage (not shown) that allows the crankchamber 5 to communicate with the suction chamber 7, an gas supplypassage (not shown) that allows the crank chamber 5 to communicate withthe discharge chamber 8, and a control valve 33 that is provided in themidstream of the gas supply passage to open and close the gas supplypassage.

When the control valve 33 opens the gas supply passage, the refrigerantflows from the discharge chamber 8 into the crank chamber 5 through thegas supply passage, so that the crank chamber pressure Pc increases.With this, the pressure balance between the crank chamber pressure Pcand the suction chamber pressure Ps decreases the inclination angle ofthe swash plate 24. As a result, piston strokes become smaller so as todecrease the discharging amount. On the other hand, when the controlvalve 33 closes the gas supply passage, the refrigerant is graduallyextracted from the crank chamber 5 to the suction chamber 7 through thegas extraction passage, so that the crank chamber pressure Pc reduces.With this, the pressure balance between the crank chamber pressure Pcand the suction chamber pressure Ps increases the inclination angle ofthe swash plate 24. As a result, the piston strokes become longer so asto increase the discharging mount. In other words, the inclination angleof the swash plate 24 reduces when the hub 25 moves toward the cylinderblock 2 and the inclination angle of the swash plate 24 increases whenthe hub 25 moves away from the cylinder block 2.

Linkage Mechanism

A linkage mechanism 40 will be explained with reference to FIGS. 3 to 7.

As shown in FIGS. 3 to 6, the linkage mechanism 40 includes an arm 41extending from the rotor 21 toward the hub 25 and an arm 43 extendingfrom the hub 25 toward the rotor 21. The arm 41 of the rotor and the arm43 of the hub are overlapped in the rotary torque transfer direction Ft(that is, the rotating direction of the drive shaft 10). With thisstructure, the rotary torque of the rotor 21 is transferred to the swashplate 24. In this example, as shown in FIGS. 3 and 4, the arm 43 isformed in a bifurcated shape having a slit S extending in the axialdirection XY (orthogonally to the rotary torque transfer direction Ft)and the arm 41 is slidably fit in the slit S in a sandwiched manner.

When the swash plate 24 rotates, the pistons 29 reciprocate so thatcompression reaction force (axial direction load Fp) from the pistons isapplied to the swash plate 24. The arm 43 of the swash plate 24 isformed with press-insertion holes 43 s (see FIG. 7) that a pin 151 ispressed into and fixed in. An axial direction load receiving face 53 isformed on an end of the arm 41 of the rotor 21. The compression reactionforce Fp is received at a contact between the pin 151 and the an axialdirection load receiving face 53.

The pin 151 extends in a tangential direction of rotary orbits of therotating member 21 and the swash plate 24, in other words, extendstoward the rotary torque transfer direction Ft. Since a largecompression reaction force (axial direction load Fp) is applied to thecontact between the pin 151 and the axial direction pressure receivingface 53 of the rotor 21, the hardness of the pin 151 and the axialdirection pressure receiving face 53 of the rotor 21 is enhanced by aquenching process or the like.

Effects

With the above described structure, the present embodiment brings aboutthe following effects.

Firstly, according to the present embodiment, the linkage mechanism 40includes an arm 41 extending from a rotor 21, an arm 43 extending from aswash plate 24 and receiving rotary torque from the arm 41 of the rotor,a pin 151 fixed to one of the arm 41 of the rotor and the arm 43 of theswash plate (the arm 43 of the swash plate, in this embodiment), and anaxial direction load receiving face 53 formed on the other of the arm 41of the rotor and the arm 43 of the swash plate (the arm 41 of the rotor,in this embodiment) and configured to contact with the pin 151 toreceive compression reaction force Fp (axial direction load) from thepistons 29.

Accordingly, the inclination angle of the swash plate 24 is changed inthe condition that great axial direction load Fp (compression reactionforce from the pistons) is applied between the pin 151 and the axialdirection load receiving face 53. However, since the pin 151 is a memberformed separately from the arm (the arm 43 of the swash plate, in thisembodiment), only the pin 151 can be quenched, etc. in a hardnessenhancement process so that the arm (the arm 43 of the swash plate, inthis embodiment) is not needed to be quenched. As a result,manufacturing cost can be reduced.

Further, since the pin 151 is separated form the arm (the arm 43 of theswash plate, in this embodiment), it is relatively easy to form theouter surface of the pin 151 to be complicated. With such a case, themanufacturing cost can be reduced comparing to the case forming the arm(the arm 43 of the swash plate, in this embodiment) to be a complicatedshape.

Further, only the pin 151 can be exchanged.

Secondly, the linkage mechanism has a structure in which one of the arms41, 43 (the arm 43 of the swash plate, in this embodiment) is formed ina bifurcated shape having a slit S and the other of the arms (the arm 41of the rotor, in this embodiment) is slidably fit in the slit S in asandwiched manner. This structure is preferable since backlash is hardlyprovided between the both arms 41, 43.

As described above, according to the present invention, the linkagemechanism includes the arm extending form the rotating member, the armextending from the tilting member and overlapped with the arm of therotating member, the pin fixed to one of the arm of the rotating memberand the arm of the tilting member, the axial direction load receivingface formed on the other of the arm of the rotating member and the armof the tilting member arm and configured to contact with the pin toreceive axial direction load between the rotating member and the tiltingmember. In this structure, the inclination angle of the tilting memberis changed in a state that great axial direction load (compressionreaction force from the pistons) is applied between the pin and theaxial direction load receiving face. However, since the pin and the armare individual members, only the pin can be quenched, etc. in a hardnessenhancement process and the arm is not required to be quenched. As aresult, the manufacturing cost can be reduced.

It is noted that the present invention should not be limited to theabove described embodiment.

For example, according to the above embodiment, the pin 51 is fixed tothe arm 43 of the swash plate and the axial direction load receivingface 53 is formed on the arm 41 of the rotor. However, in the presentinvention, as shown in the first modification in FIG. 8 and the secondmodification in FIG. 9, the axial direction load receiving face 53 maybe formed on the arm 43 of the swash plate and the pin 151 may be fixedto the arm 41 of the rotor.

According to the above embodiment, a slit S is provided to the arm 43 ofthe swash plate and the arm 41 of the rotor is slidably held in the slitS. However, in the present invention, as shown in the secondmodification in FIG. 9 and the third modification in FIG. 10, the slit Smay be provided to the arm 41 of the rotor and the arm 43 of the swashplate may be slidably fit in the slit S.

According to the above embodiment, the cross-section of the pin is acircular shape; however, in the present invention, it may be formed inother shapes.

Further, according to the above embodiment, the swash plate 24 is madein combination of the swash plate body 26 and the hub 25 which areseparately formed; however, in the present invention, the swash platebody and the hub may be formed integrally in advance to constitute theswash plate. Further, the above embodiment employs a sleevelessstructure in which the swash plate 24 is directly attached to the driveshaft 10 without any sleeve; however, in the present invention, theswash plate may be attached to the drive shaft via a sleeve.

INDUSTRIAL APPLICABILITY

The present invention may be applied to not only a swash plate typevariable displacement compressor but also a wobble plate type variabledisplacement compressor and the present invention may be implementedwith various modifications.

1. A variable displacement compressor, comprising: a drive shaft; arotating member fixed to the drive shaft and rotating integrally withthe drive shaft; a tilting member attached to the drive shaft and beingchangeable a tilt thereof with respect to an axis of the drive shaft; alinkage mechanism configured to rotate the rotating member and thetilting member integrally with allowing the tilt of the tilting memberto change; and a piston reciprocating in a cylinder bore correspondingto rotary movement of the tilting member; wherein the linkage mechanismincludes: an arm extending from the rotating member; an arm extendingfrom the tilting member and overlapping with the arm of the rotatingmember in a rotating direction; a pin fixed to one of the arm of therotating member and the arm of the tilting member; and an axialdirection load receiving face formed on the other of the arm of therotating member and the arm of the tilting member and configured tocontact with the pin to receive an axial direction load applied betweenthe rotating member and the tilting member.
 2. The variable displacementcompressor according to claim 1, wherein the arm of the rotating memberis formed in a bifurcated shape divided by a slit to slidably hold thearm of the tilting member in a sandwiching manner.
 3. The variabledisplacement compressor according to claim 1, wherein the arm of thetilting member is formed in a bifurcated shape divided by a slit toslidably hold the arm of the rotating member in a sandwiching manner.